Volt Appearing Between White Neutral And Gnd Wire ?

Very normal. The earth wire, and neutral, are joined nominally at one point. When power is drawn between live and neutral in the system, the resistance between the point where the power is drawn, and the connection, will result voltage being present, between the neutral and the ground, if measured anywhere but at the connection point.

Best Wishes

I read in sci.electronics.design that Robert11 wrote (in ) about 'Volt Appearing Between White Neutral And Gnd Wire ?', on Wed, 27 Apr 2005:

No. The neutral wire is not a superconductor, and it carries currents.

Even 'ground potential' can mean different things in different places. There OUGHT not to be any current in the ground conductor, unlike the neutral, so its potential SHOULD be the same everywhere, but there always are leakage currents, so even the 'ground' ground isn't perfect.

ANY piece of wire has resistance. This applies to neutral wires and ground wires. What you are seeing, from your description, is the voltage dropped across the resistance of the neutral wire due to the current flowing in it. Where that current is coming from is not determinable by what you have told us

It is a bit high, but....

neutral and ground ?

drawn between live and neutral in the system, the

will result voltage being present, between the neutral

With other words, if you disconnect all the mains powered devices in your house (especially the heavy loads, such as a stowe) this voltage falls down to

The house I stayed in Ottawa also connected the "green" wire to the water pipe.

The house was supplied by a well. Two inches from the ground connection, the copper pipe connected to a plastic pipe that ran though the concrete to the outside well.

So all the grounds were connected together, but they didn't connect to anything!

It passed inspection by the building inspector. Rules said the ground had to connect to the water pipe. It did.

Mike Monett

In article , SioL wrote: [...]

(USA location specific)

Depending of the house etc, you may also have to shut off the power next door to get it really down to zero. In some places there are two connections to earth the ground, one for the white and one for the green. This is done so that ground return current in the white can't raise the voltage on the green. A small AC voltage can still be seen even with the main breaker to the house pulled.

I saw about 10mV in the one case where I measured. That was on a house built before the "bonded" grounding was required. The "green" wire was actually a bare wire that ran back to the water pipe.

Hello Gents, reading this thread brought back memories of a bad experience when I was an apprentice in the late 1960s.

I was doing a few months experience in a cal lab and was working on an old chart recorder. The 240 volt input connector was a Bulgin type. Old fashioned now.

I was fascinated by this 3 or 4 volts appearing between earth and neutral as it seemed like a source of free power. I had heard stories of one fellow running low voltage globes permanently in his outside brick toilet. Energy for free!

Here was the Active Neutral and Earth exposed in front of me inside this chart recorder so I thought I would make a few measurements.

I was using a couple of AVO model 8 multimeters to poke around the rear of this small mains input connector of the chart recorder. The old AVO meter test prods were massive by to-days standards. One meter was measuring the volts between Neutral and Earth, about 3 or 4.

I used resistors as loads and the second AVO meter to measure current. The voltage dropped readily. I reduced the load resistor to near zero ohms by shorting out the the neutral to earth via the second AVO meter. I noted that the meter reading was roughly 2 amps. The voltage between Neutral and Earth dropped to zero as expected. Then Flash Bang! The work shop was in darkness! The large meter prods slipped off the back of the Bulgin mains connector. One meter prod was melted.

"No problem," said the boss. "just reset the circuit beaker on the power box outside." I had never seen a circuit breaker before but I saw that one of lever switches was not in the same position as the rest so I tried moving it. I tried several times to move it in to position and it just kept buzzing and returning to the off position.

I returned to the workshop to tell my fellow workers that the circuit breaker will not stay in position only to find them staring at a very blackened chart recorder then glaring at me. The chart recorder had been emitting smoke and sparks each time I was attempting to reset the circuit breaker. I hadn't unplugged the chart recorder when I was told to reset the circuit breaker outside the building. Boy did I cop it from the boss! I didn't tell the boss what I was really doing, "just measuring the mains supply according to procedures in the book and my meter prod slipped." I don't think he believed me.

I worked my arse off cleaning up the insides of that chart recorder. Some of the black shit would not come off resistors and capacitors so I ran around trying to find replacements.

I learned about "carbon tracking" that was caused between the pins of the Bulgin mains connector when the multimeter prod fell across the pins and shorted the 240V supply. I learned what a circuit breaker was. I learned not to mess with customers gear. I learned a lot that day! Never to be forgotten!

Regards John Crighton Sydney

The inspector was wrong the NEC clearing states that in that case there HAS to be a ground wire. I'm just going through some of that stuff now, in the book it is recommended that the wire be the same gauge as the wires for L1 and L2 combined but it also says in most case the wire just has to have the same current carrying cap as either L1 or L2. Pat

HAS

the

L1

the

The house I'm moving into this weekend has some knob and tube wirring, that stuff is scarey! PAt

Taking a shower could be fun in such a house :)

wirring, that

Post us some pics :) Its a real rarity here in UK.

NT

to

pipes

concrete floors make quite good earths, especially wet bathroom ones.

zero.

you

NT

It actually would be safe unless you watered the garden. The water pipes would be the only return path you could touch inside the house. Everything could be at 1000V so long as nothing you can touch is at zero.

The water in the garden hose could be at 120V and, on some hot day, you decide to run through the sprinkler in bare feet.

In article , Pat Ford wrote: [...]

I assume that is the current standard. It is not unreasonable to assume that at an earlier date, it did not contain that text. Back when plastic pipe had never been heard of, it would be natural for them to assume a metal pipe. At one time, "knob and tube" wiring was the standard.

An electrical inspector is required to inspect to the current NEC, not an obsolete one.

I read in sci.electronics.design that Guy Macon wrote (in ) about 'Volt Appearing Between White Neutral And Gnd Wire ?', on Thu, 28 Apr 2005:

But what if the inspector is of similar vintage to the obsolete standard? (;-)